The present invention broadly relates to a device for the production of a reaction mixture which forms massive or foamed plastic materials from liquid components. The device has a housing with a guide bore provided therein for an ejection piston. Feed lines with entry openings and recirculation lines are provided. The device is also provided with a rotary slide valve, which contains a mixing chamber through which the ejection piston can pass. The slide valve is movable in a position that frees the entry openings to the mixing chamber to connect the entry openings through flow channels provided in the rotary slide valve with the recirculation lines.
A device of the above type, is described in German Offenlegungsschrift No. 33 01 911. The disclosed device has a rotary slide valve whose axis coincides with that of the mixing chamber, with the mixing chamber centrally arranged in the rotary slide valve. This rotary slide valve which has the shape of a sleeve has injection channels, which can be aligned with the feed lines by rotating. These injection channels must be cleaned through an extensive ejection mechanism after each mixing process. Such a cleaning control is quite costly. A major disadvantage of this device is that the mixing chamber is completely open toward the exit as in a common ejection piston mixhead and is consequently not suited for components that are difficult to mix.
It is the object of this invention to create a device of the above-mentioned type, which is less costly and is suitable for difficult mixing projects.